View Full Version : Marking cam pins?
This is an interesting idea: https://www.forwardcontrolsdesign.com/SCP-SOTAR-Cam-Pin_p_206.html However I don't see why I can't mark a cam pin myself. Would it be OK to make a small notch in the region of the dimple using an abrasive stone or file?
63340
This is an interesting idea: https://www.forwardcontrolsdesign.com/SCP-SOTAR-Cam-Pin_p_206.html However I don't see why I can't mark a cam pin myself. Would it be OK to make a small notch in the region of the dimple using an abrasive stone or file?
Shouldn’t hurt anything......seems like a great idea
This is an interesting idea: https://www.forwardcontrolsdesign.com/SCP-SOTAR-Cam-Pin_p_206.html However I don't see why I can't mark a cam pin myself. Would it be OK to make a small notch in the region of the dimple using an abrasive stone or file?
63340
It’s fine. Or use the same punch you use to stake your castle nuts.
titsonritz
08-06-20, 21:22
It's not a bad idea, I think I'll center punch my cam pins.
https://www.youtube.com/watch?v=VuZ4TgoR1Zk&feature=emb_title
Ive had cam pins that have crazy groves in them when I cleaned them last. It was strange and didn't look normal.
Edit: Damn that video explained exactly what I was referring. But I dont understand why flipping them around makes any difference. I hear the guy but dont understand why it matters. Educate me Titsonritz.
PB
It's not a bad idea, I think I'll center punch my cam pins.
From the video you just posted: "you can't just grab a punch and start banging on this" which is why I plan to use an abrasive file.
titsonritz
08-06-20, 22:54
From the video you just posted: "you can't just grab a punch and start banging on this" which is why I plan to use an abrasive file.
Without f'ing up your punch, I have a few sacrificial center punches that will get the job done.
titsonritz
08-06-20, 23:09
Ive had cam pins that have crazy groves in them when I cleaned them last. It was strange and didn't look normal.
Edit: Damn that video explained exactly what I was referring. But I dont understand why flipping them around makes any difference. I hear the guy but dont understand why it matters. Educate me Titsonritz.
PB
Because the wear becomes consistent, essentially forms a custom fit. Flipping it around will make different wear on both sides. Picture this, if you never once removed your cam pin it will have a little on one side and lot on the opposite side, if you flip it around it will wear a lot on both sides. This wear will over time will oblong the cam pin hole in the bolt. The two most common places a bolt will fail are the lugs on either side of the extractor and the cam pin hole. I'm sure it is a minor issue and will only come into play with high volume users, but I'll take what I can get for nothing but a consistent practice. At least that is what I'm getting out it and hope my dribble makes sense as I'm a few drinks deep.
I think FCD's site description is perfectly accurate when it calls this as a "why didn't I think of it" moment.
Because the wear becomes consistent, essentially forms a custom fit. Flipping it around will make different wear on both sides. Picture this, if you never once removed your cam pin it will have a little on one side and lot on the opposite side, if you flip it around it will wear a lot on both sides. This wear will over time will oblong the cam pin hole in the bolt. The two most common places a bolt will fail are the lugs on either side of the extractor and the cam pin hole. I'm sure it is a minor issue and will only come into play with high volume users, but I'll take what I can get for nothing but a consistent practice. At least that is what I'm getting out it and hope my dribble makes sense as I'm a few drinks deep.
I think FCD's site description is perfectly accurate when it calls this as a "why didn't I think of it" moment.
While I respect Roger and Chads perspective on marking a cam pin. My 2cents after seeing functional cam pins on several suppressed short machine guns with 20k plus rds over the years is just inspect it then spend the 8 bucks when it wears out.
I've been marking mine with a sharpie. I have yet to see if the mark fades after furring. But if it does, then just wipe of the carbon, oil, grease or whatever and mark it again before dissembly.
There is always a lot of controversy about the videos and content from my courses. It's not intentional, nor am I offended if people politely disagree.
Marking the cam pin has less to do with saving the life of the cam pin and more to do with extending the life of the bolt.
The more you do to minimize wear and slop between the bolt and cam pin, the longer the bolt should last.
When you allow excessive amounts of slop between the cam pin and the bolt, you increase the chance of stretching or breaking the thin webbing at the edges of the cam pin bore.
I have done extensive testing using custom ground gage pins to track when wear becomes a concern. Some people have a philosophy where they shoot until something breaks or fails. I like to know before something breaks or fails so I can avoid a catastrophic malfunction.
FWIW, I mark my cam pins with a starter drill bit.
But I dont understand why flipping them around makes any difference.
It doesn't. PURE NONSENSE!!!
20 plus years on this gun, and this has to be the top 5 dumbest f@cking bullshit I've ever seen.
Keeping an open mind, and I always appreciate a quality technical discussion.
I would be interested in observations and data comparing this directional cam pin practice in GTG vs good-as bolts.
I have done extensive testing using custom ground gage pins to track when wear becomes a concern. Some people have a philosophy where they shoot until something breaks or fails. I like to know before something breaks or fails so I can avoid a catastrophic malfunction.
FWIW, I mark my cam pins with a starter drill bit.
Thank you.
While I respect Roger and Chads perspective on marking a cam pin. My 2cents after seeing functional cam pins on several suppressed short machine guns with 20k plus rds over the years is just inspect it then spend the 8 bucks when it wears out.
The nitride FCD pins are/will be priced at less than $10, which isn't too Gucci to give them a shot. If they were available to order.
Andy
NP3 SCP (SOTAR Cam Pin) is subject to Robar delays, which can run months at a time. Nitrided SCPs will be shipping again in 3 weeks.
As Chad pointed out, it isn't about preserving the cam pin but more about reducing the subsequent wear introduced to the bolt. If you can do something (don't need to buy ours) by simply marking it and reinstalling it in the same orientation each time for free, I don't see why some are up in arms about it. End users aren't spending $10 to preserve a $8 part, but the bolt. Or don't, and replace the bolt and cam pin as needed.
We respect Chad a great deal, and know he doesn't do something because it's trendy, there is his considerable professional experience and knowledge behind it. This runs parallel with our design philosophy of "nothing without a purpose or reason", we don't make decorations.
NP3 SCP (SOTAR Cam Pin) is subject to Robar delays, which can run months at a time. Nitrided SCPs will be shipping again in 3 weeks.
As Chad pointed out, it isn't about preserving the cam pin but more about reducing the subsequent wear introduced to the bolt. If you can do something (don't need to buy ours) by simply marking it and reinstalling it in the same orientation each time for free, I don't see why some are up in arms about it. End users aren't spending $10 to preserve a $8 part, but the bolt. Or don't, and replace the bolt and cam pin as needed.
We respect Chad a great deal, and know he doesn't do something because it's trendy, there is his considerable professional experience and knowledge behind it. This runs parallel with our design philosophy of "nothing without a purpose or reason", we don't make decorations.
Amen guys
I have a technical question: how effective is the NP3 coating if it more or less wears away as the pin is grooved? Would the harder nitrided finish be superior in this case?
Sent from my Pixel 3a XL using Tapatalk
Dr. Bullseye
08-07-20, 12:11
The nitride FCD pins are/will be priced at less than $10, which isn't too Gucci to give them a shot. If they were available to order.
Andy
Well, for the same price you can get three cam pins from Del-ton or two from BCM. In fact you can get a whole bolt for $45.00 from Del ton which would be about the cost of two of these marked cam pins plus shipping. If making with a sharpie actually works, what is the issue in doing that?
NP3 SCP will always be hard to find because we piggyback with SIONICS schedule to send stuff to Robar for coating. At the time it was expedient, and we didn't expect to sell many SCPs.
NP3 SCPs for your NP3 coated BCGs, nitride for your phosphated or nitrided BCGs. You can do it yourself, just remember to refinish it so the spot you carved on the cam pin won't rust.
Well, for the same price you can get three cam pins from Del-ton or two from BCM. In fact you can get a whole bolt for $45.00 from Del ton which would be about the cost of two of these marked cam pins plus shipping. If making with a sharpie actually works, what is the issue in doing that?
I don't see anything in my post that reflects any issues at all. I simply commented that I felt the price is not out of line. That is my opinion on most, if not all, of the FCD parts (which I don't have many of). They offer a better mousetrap at a reasonably price increase. If you don't agree, don't buy from them, it's pretty simple.
Andy
Clandestine and Duffy - thanks for the info and your courtesy in sharing.
This is a technical thread in a technical subforum. If your contribution doesn't offer something toward that end, post it elsewhere.
NP3 SCP will always be hard to find because we piggyback with SIONICS schedule to send stuff to Robar for coating. At the time it was expedient, and we didn't expect to sell many SCPs.
NP3 SCPs for your NP3 coated BCGs, nitride for your phosphated or nitrided BCGs. You can do it yourself, just remember to refinish it so the spot you carved on the cam pin won't rust.
Roger, I like your stuff...so I bought a few NP3. Seems like a well thought out idea. I don't have NP3 bolts just phosphates and a nitride one...any issues with using the NP3 ones in the phosphate BCG? Or I could buy some NP3 bolts...lol
I also thought Robar was closing or something along those lines?
Five_Point_Five_Six
08-08-20, 15:42
I think Chad's knowledge and experience along with Roger Wang's reputation are deserving of respect instead of just being dismissed and ranting about shooting dirt clods in the desert for 30 years.
I too kinda scoffed at the idea until listening to the explanation by Chad and Roger and why it could be beneficial. Neither of them have said it's mandatory, and Roger even said if you want to mark your own instead of buying his that's okay too. I've been at this for more than 20 years and the more time passes the more I realize how much I don't know.
Nevermind. I'm not here to argue.
So are the loads on the cam pin not evenly distributed? This is what leads to uneven wear?
Straight Shooter
08-08-20, 20:18
WHY, until this thread, has nobody NOWHERE ever said ANYTHING anywhere about this being an issue?
Im several decades into the AR, first Ive heard of it. Has this been reported as an issue ANYWHERE else?
Im ASKING..not denying..hell I dont know.
WHY, until this thread, has nobody NOWHERE ever said ANYTHING anywhere about this being an issue?
Im several decades into the AR, first Ive heard of it. Has this been reported as an issue ANYWHERE else?
Im ASKING..not denying..hell I dont know.
I think it's because the understanding of the weapon has evolved over time. Just like inventors such as Jim Sullivan have made improvements over the years.
The more that is learned and the more data that gets examined, helps to understand better what's going on. Does it matter to 95% of people ? Probably not.
Some people are just into the science, pretty much that way with anything really.
For what it's worth, the subject of cam pin wear comes up with boring regularity.
This thread discussed cam pin wear, bolt breakage, and marking cam pins to install them in the same direction each time: https://www.m4carbine.net/showthread.php?134117-Cam-pin-wear-as-a-contributor-to-bolt-failure
Andy
No issues with NP3 cam pins in phosphated BCGs :) We'll have a bunch of nitrided SCPs in 3 weeks.
Robar's retail facing operation closed, but not the industry side of it.
Roger, I like your stuff...so I bought a few NP3. Seems like a well thought out idea. I don't have NP3 bolts just phosphates and a nitride one...any issues with using the NP3 ones in the phosphate BCG? Or I could buy some NP3 bolts...lol
I also thought Robar was closing or something along those lines?
Chad's experience as a practicing gunsmith is a big part. He's a straight shooter, he has no hidden agendas and self benefiting motives. SCP was my idea to make this better known. For what we charge, this almost qualifies as a free public service. Chad agreed to let us use his name (SOTAR), we didn't file a design patent (however useless it is), not sure if we can file a utility patent since prior arts exist. You read this correctly, it's been done before and since. Centurion Arms and G both have positional markings on their cam pins. You can mark the pins yourself, can be something as simple as a tiny notch or dimple, as long as you know which way should always face the front, or rear. A good idea like this should be freely share and it is so, as you guys share your experience and ideas on M4C.
So if larger companies do it, would it seem more legitimate? Larger companies aren't necessarily on the forefront of putting new ideas, or good ideas into designs. We're a tiny shop, I remember when folks used to say things like solutions in search of a problem simply because the solutions weren't made for them and don't apply to them. To an able bodied person, a wheelchair is a solution in search of a problem. "It never happens to me", or "100rds, no problems" are typically dismissed as insufficient as well.
I think Chad's knowledge and experience along with Roger Wang's reputation are deserving of respect instead of just being dismissed and ranting about shooting dirt clods in the desert for 30 years.
I too kinda scoffed at the idea until listening to the explanation by Chad and Roger and why it could be beneficial. Neither of them have said it's mandatory, and Roger even said if you want to mark your own instead of buying his that's okay too. I've been at this for more than 20 years and the more time passes the more I realize how much I don't know.
No issues with NP3 cam pins in phosphated BCGs :) We'll have a bunch of nitrided SCPs in 3 weeks.
Robar's retail facing operation closed, but not the industry side of it.
Thank you!
I never knew, or even thought about this. Why the hell would they have not taught me that, all those years ago, in the Marines? Seems to make sense.
He's a straight shooter, he has no hidden agendas and self benefiting motives. SCP was my idea to make this better known.
so is it SOTAR in name only?
Chad's experience as a practicing gunsmith is a big part. He's a straight shooter, he has no hidden agendas and self benefiting motives. SCP was my idea to make this better known. For what we charge, this almost qualifies as a free public service. Chad agreed to let us use his name (SOTAR), we didn't file a design patent (however useless it is), not sure if we can file a utility patent since prior arts exist. You read this correctly, it's been done before and since. Centurion Arms and G both have positional markings on their cam pins. You can mark the pins yourself, can be something as simple as a tiny notch or dimple, as long as you know which way should always face the front, or rear. A good idea like this should be freely share and it is so, as you guys share your experience and ideas on M4C.
So if larger companies do it, would it seem more legitimate? Larger companies aren't necessarily on the forefront of putting new ideas, or good ideas into designs. We're a tiny shop, I remember when folks used to say things like solutions in search of a problem simply because the solutions weren't made for them and don't apply to them. To an able bodied person, a wheelchair is a solution in search of a problem. "It never happens to me", or "100rds, no problems" are typically dismissed as insufficient as well.
Thanks my friend.
Centurions people took my class. Their feed ramp work changed and they started marking cam pins afterward.
People trash me for marking cam pins and feed ramp work.
I think what Chad talked about makes sense, and wanted a version of it. While Chad marks his differently, we use the minimalist approach and just gave it a dot/dimple. We give credit where credit is due, we learned it from Chad so SCP's namesake pays homage to SOTAR and Chad, it's also a way for us to acknowledge Chad and SOTAR's contribution. I obtained permission from Chad to use the name SOTAR in SCP's naming, Chad didn't want financial compensation, nor does he carry and sell them to his students.
Chad was also the one that notified us when some of our CNFs (castle nuts) were inconsistent in their threads, we subsequently changed production so all CNFs now are made by Swiss machines, tested and gauged in ways no other castle nuts are. If you guys wonder what we meant by we benefited from Chad's knowledge and experience, these are but two of the instances where he is directly responsible in us making changes to improve our products.
so is it SOTAR in name only?
After reading this thread, I've come to the conclusion that if one chooses to do so, so be it, it's their peace of mind. Now in the same vein, if people start marking their firing pin retaining pins so that the pin is vertically orientated the same way each time, then there's going to be some epic rebuttals! I base this on my observation of the excessive use of "witness marks". I'm sure we've all seen how that can get carried away. :p
Seems reasonable and inline with keeping a bolt matched with a barrel instead of sharing it between uppers causing new/different wear on the bolt and extension lugs with each swap.
Paint pens.....not just for marking screws.
Dr. Bullseye
08-12-20, 18:37
Paint pens.....not just for marking screws.
Someone try again to talk me into a tiny hole drilled in the top of the cam pin for $19.00 vs. a marking pen and a $4.50 cam pin? I don't want to hear about someone's reputation. I want something factual.
Someone try again to talk me into a tiny hole drilled in the top of the cam pin for $19.00 vs. a marking pen and a $4.50 cam pin? I don't want to hear about someone's reputation. I want something factual.
No one is trying to do that.
Pretty sure they said mark it yourself if you want. I did.
But I did this with a chrome BCG I had.
Here’s how I understand it:
Factual: keeping the cam pin pointed the same direction will produce consistent wear.
Proposition: this more consistent wear may prolong strength and therefore lifespan of bolt.
Reality: no one has done an extended study to prove this.
Opinion: If it doesn’t cost anything, why not? If it costs a few extra dollars for an NP3 cam pin when I need one, why not consider it?
Robar charges us $7 to NP3 each cam pin, add shipping both ways, I wasn't kidding when I said this almost qualifies as a loss leader in case anyone thinks we're making off like bandits.
Robar charges us $7 to NP3 each cam pin, add shipping both ways, I wasn't kidding when I said this almost qualifies as a loss leader in case anyone thinks we're making off like bandits.
Yeah, people act like you have a monopoly and are forcing them to buy your products. I don't have to buy a Porsche to appreciate them.
Andy
Dr. Bullseye
08-13-20, 11:40
No one is trying to do that.
Pretty sure they said mark it yourself if you want. I did.
But I did this with a chrome BCG I had.
Here’s how I understand it:
Factual: keeping the cam pin pointed the same direction will produce consistent wear.
Proposition: this more consistent wear may prolong strength and therefore lifespan of bolt.
Reality: no one has done an extended study to prove this.
Opinion: If it doesn’t cost anything, why not? If it costs a few extra dollars for an NP3 cam pin when I need one, why not consider it?
Then let me say this another way. Let's assume the theory of mounting the pin in the same direction each time decreases wear is correct.
1. There is a $19.00 cam pin with a little hole in the top to mark direction.
2. There is a mil spec cam pin for say $6.50 with a marking pen's mark made on one side to mark direction.
Which one is provably better?
You are arguing with yourself, and still off point. You are comparing an NP3 cam pin to a milspec cam pin. Sionics NP3 cam pin is $15, and the FCD SCP is $17, so that’s $2 upcharge for the orientation marking.
Just buy the milspec cam pins and mark them with a paint pen.
I swear man, the lack of reading comprehension and self importance on the Internet never ceases to amaze me.
This part isn't technical in nature.
We buy cam pins and ship them to one of the shops we work with to dimple and refinish them, shipping charges and shop charges add up, hence there isn't much of a price difference between the two now.
We now have the pins made for us with a dimple drilled already. This will bring the nitrided version price down quite a bit. NP3 version of anything is expensive, we don't argue anyone needs NP3 coated BCGs or cam pins, but the option is there.
Roger,
I think you have been very reasonable in explaining everything.
Some people just can't be reasoned with my friend.
Five_Point_Five_Six
08-13-20, 14:35
For what it's worth Chad and Roger, this is also the same guy that thinks Ultradyne sights are faster than a red dot.
Roger and Chad- Thank you both very much for your quality contributions to this technical subforum. You are appreciated.
ColtSeavers
08-13-20, 16:16
Damn, this thread is a wreck.
I'd also like to thank Duffy and clandestine though.
For what it's worth Chad and Roger, this is also the same guy that thinks Ultradyne sights are faster than a red dot.
That’s right!
Another big Thanks to Roger and Chad for this helpful info. It gives me something to think about and options on how to address this bit of information.
Cheers, Steve
Thank you for having me gentlemen. I am going to do my very best to contribute more.
Thanks guys for allowing us to talk about our products sometimes :)
Thanks guys for allowing us to talk about our products sometimes :)
Got mine today in the mail..impressive and I will install at some point this weekend in one of my rifles before going to the range..
Thanks!
You are arguing with yourself, and still off point. You are comparing an NP3 cam pin to a milspec cam pin. Sionics NP3 cam pin is $15, and the FCD SCP is $17, so that’s $2 upcharge for the orientation marking.
Just buy the milspec cam pins and mark them with a paint pen.
I swear man, the lack of reading comprehension and self importance on the Internet never ceases to amaze me.
Amen! Thread goes from listing the rationale of a product to bickering about a few bucks on a frigging cam pin.
Dr. Bullseye
08-13-20, 21:45
For what it's worth Chad and Roger, this is also the same guy that thinks Ultradyne sights are faster than a red dot.
It is.
Dr. Bullseye
08-13-20, 21:48
Guys, each and every time you bring up this Gucci crap and say it is somehow better than mil spec, I am going to ask why and for some proof.
Thank you for having me gentlemen. I am going to do my very best to contribute more.
Thanks guys for allowing us to talk about our products sometimes :)
Thank you both for sharing. I'll go this route when I pick up spares.
Guys, each and every time you bring up this Gucci crap and say it is somehow better than mil spec, I am going to ask why and for some proof.
Everything I do is about experience and data. If you don't accept the free advice it does not hurt my feelings.
Thanks guys for allowing us to talk about our products sometimes :)
Chad and Roger, I am fairly sure the vast majority of people on this forum (including myself) welcome and value your input.
Keeping this post on topic, I'm not sure how I feel about the cam pin orientation. Over the years, sometimes I reinstall them in the same orientation. But sometimes I flip them around to get more even wear out of them, trying to make them last longer (like rotating tires on a car). However, most of the time I don't pay attention to the orientation.
I do think cam pin wear is an often overlooked cause of bolt breakage. So I probably replace mine more often than most just as preventative maintenance.
I noticed that some bolt carriers chew up cam pins simply because of the rough or inexact machining of the cam pin path in the bolt carrier.
Joe Mamma
Five_Point_Five_Six
08-14-20, 10:13
It is.
For you, probably.
Roger in my mind is beyond the shade that is thrown his way. He is one of the most generous dudes you will find in this industry. I am kinda sick of ppl trying to throw him under the bus for price -like he is somehow counting his money by the bundle.
Chad is a super knowledgeable guy. You don't even have to like him to take advantage of his experience. Go figure.
ppl trying to throw him under the bus
we call those ppl trolls
It's all good gents, not everyone sees things our way, we don't expect them to.
SCP shouldn't be controversial, it's something you can do if you have a mind to get every bit of performance you can simply by installing it back in the same orientation. Or if you don't believe in it, don't do it, and replace the cam pin when it's got more slop than you're comfortable with. Loose fitting parts beat on each other more than tighter fitting parts when they're in motion, this is true of other things in life too.
Similarly, some question the usefulness of Ned's OCKS. While it is true that properly torqued and staked carrier gas keys rarely, if ever come loose, so why OCKS? It goes back to the idea of getting every ounce of performance, in this case reliability, out of something as simple as a pair of well designed gas key screws. Carriers with OCKS are more tolerant of variables that may be introduced during toruqing and staking, OCKS doesn't replace either. A properly torqued and staked gas key using OCKS is very difficult, and much harder to loosen than with typical gas key screws. Chad's video has demonstrated this time and again in his videos. For the minimal cost, maybe a better question isn't why, but why not.
For those that agree with us, there's the option :)
FCD is about as far from Gucci/lifestyle/hobby grade as it gets. The price of our products may put us in the boutique space, it's not by design and I don't like it. US sourced material, and American labor aren't cheap, but we're an American company, and will only use American material and workforce. So our products are expensive, you can take comfort in that your dollars go down the chain and do their part to keep our dealers and shops with their American employees in business.
US sourced material, and American labor aren't cheap, but we're an American company, and will only use American material and workforce.
:cool:
Ned Christiansen
08-15-20, 14:16
I never gave this a bit of thought but after the discussion I'm ready to say "it matters". Does it matter a ton? Well, does any mod, any improvement matter that much? There is nothing I can think of, no modification, no accessory, no lube, nothing-- that makes an AR "twice as good". And yet, if it helps keep the bolt in one piece to x-number of rounds more, or even until the day after the big gunfight as opposed to the day of, I would say then that it's worth it. I mean the system is pretty darn good as-is, assuming some quality and care in manufacture, so at this point we are looking for things that make it a "little" better. A 30%, or a 10%, or even a 2% increase in bolt life could be of value in terms of money and convenience but it could also mean much more.
I will say that I can't fault the logic that Chad and Roger are putting forth. Bolt breakage at the cam pin hole in my opinion comes from the cam pin impacting the front terminus of the carrier's cam pin slot-- pushing the rear part of the bolt to the rear, but pulling the front part. Add in some other factors, mostly poorly made bolts where the knife-edge intersection of the cam pin hole and body diameter are notched. Notches are cracks waiting to be born. Sprinkle in other manufacturing shortcuts like material or heat treat and maybe a little hard extraction (thousands of times)... I'll just say that for me I think going forward it's worth marking them or getting new ones that are marked.
Wrong answer.
This thread is about marking cam pins, not iron sights. Here's a link for you to use to go start your own thread discussing the merits of said irons: https://www.m4carbine.net/newthread.php?do=newthread&f=3
Back on topic, this thread is interesting to me because it's such a simple concept but something I hadn't considered before. It never hurts to have a solid reference point for wear on a part.
I never gave this a bit of thought but after the discussion I'm ready to say "it matters". Does it matter a ton? Well, does any mod, any improvement matter that much? There is nothing I can think of, no modification, no accessory, no lube, nothing-- that makes an AR "twice as good". And yet, if it helps keep the bolt in one piece to x-number of rounds more, or even until the day after the big gunfight as opposed to the day of, I would say then that it's worth it. I mean the system is pretty darn good as-is, assuming some quality and care in manufacture, so at this point we are looking for things that make it a "little" better. A 30%, or a 10%, or even a 2% increase in bolt life could be of value in terms of money and convenience but it could also mean much more.
I will say that I can't fault the logic that Chad and Roger are putting forth. Bolt breakage at the cam pin hole in my opinion comes from the cam pin impacting the front terminus of the carrier's cam pin slot-- pushing the rear part of the bolt to the rear, but pulling the front part. Add in some other factors, mostly poorly made bolts where the knife-edge intersection of the cam pin hole and body diameter are notched. Notches are cracks waiting to be born. Sprinkle in other manufacturing shortcuts like material or heat treat and maybe a little hard extraction (thousands of times)... I'll just say that for me I think going forward it's worth marking them or getting new ones that are marked.
This.
I look up to Ned.
His post made me smile. I'm always learning from that man. :)
hotrodder636
08-15-20, 22:39
I don’t understand why some people are so butthurt and emotionally charged about this. The idea makes sense, consistent wear on bearing surfaces. You can mark it yourself or get an FCD pin, either will accomplish the same thing.
Chad and Roger have gave clear explanations and Ned put the cherry on top by explaining the squeezing of that next little drop of reliability/performance.
If you don’t like the idea, move on. Dang people. Threads like this are why we continue to lose SMEs from this forum. We should be grateful to have the Chads, Rogers and Neds here sharing experience and knowledge.
If you don’t like the idea, move on. Dang people. Threads like this are why we continue to lose SMEs from this forum. We should be grateful to have the Chads, Rogers and Neds here sharing experience and knowledge.
Sad but true. And we have lost a bunch over the years. Back when I joined, the common sense nature and not putting up with misinformation was what I enjoyed, along with the SME's. Now it's a crapshoot what you get when you login.
Dr. Bullseye
08-16-20, 13:13
For what it's worth Chad and Roger, this is also the same guy that thinks Ultradyne sights are faster than a red dot.
Hey Vegas, where are your comments for this? Did you send him a link? Did you tell him he was in the wrong thread? I did not bring up Ultradynes, he did. So either send him a link or just maybe some of you technical experts can answer my questions. I am still waiting. Why is a dimple on a cam pin any better than a mark with a sharpie? Is his the $12-$14.00 you pay for the dimple? Get me a fact.
Five_Point_Five_Six
08-16-20, 15:03
Hey Vegas, where are your comments for this? Did you send him a link? Did you tell him he was in the wrong thread? I did not bring up Ultradynes, he did. So either send him a link or just maybe some of you technical experts can answer my questions. I am still waiting. Why is a dimple on a cam pin any better than a mark with a sharpie? Is his the $12-$14.00 you pay for the dimple? Get me a fact.
I didn't bring them up as a topic of discussion, I brought it up to give them a frame of reference as to why they shouldn't be concerned with your opinion or remarks. No one cares if you mark your cam pins or not, and no one has said you had to. Go back and read Ned's post, or don't, and continue on ignoring the facts that have been laid out in front of you by them.
Hey Vegas, where are your comments for this? Did you send him a link? Did you tell him he was in the wrong thread? I did not bring up Ultradynes, he did. So either send him a link or just maybe some of you technical experts can answer my questions. I am still waiting. Why is a dimple on a cam pin any better than a mark with a sharpie? Is his the $12-$14.00 you pay for the dimple? Get me a fact.
See below or above on the wrong thread stuff, I think 5.56 covered it perfectly.
I'm not a technical expert or here to disprove anything one way or the other. In fact I said above "It never hurts to have a solid reference point for wear on a part". That is my belief and opinion that comes with no warranty or refunds. Take what the SME said and decide for yourself whether it applies to you or not. Me, I would try the part and run it side by side and decide for myself. $12-$14 isn't going to change my world and if it does for you, you have bigger problems than cam pin wear.
I guess bottom line, don't like, don't buy but appreciate that there are industry heads willing to share their opinion and experience here and that maybe, just maybe it might mean something. I certainly appreciate their insight and don't begrudge their need to make a living.
I didn't bring them up as a topic of discussion, I brought it up to give them a frame of reference as to why they shouldn't be concerned with your opinion or remarks. No one cares if you mark your cam pins or not, and no one has said you had to. Go back and read Ned's post, or don't, and continue on ignoring the facts that have been laid out in front of you by them.
Why is a dimple on a cam pin any better than a mark with a sharpie? Is his the $12-$14.00 you pay for the dimple? Get me a fact.
Come on, man. Stop being obtuse. The dimple is better than the sharpie mark because it is permanent and doesn't require that you have a sharpie on your bench or in your bag, It also eliminates the possibility that you will accidentally mark it wrong - which could happen if you dropped the part or mishandled it.
Both Chad and Duffy pointed out ways that you could mark them yourself.
As to is it worth it? Well, I couldn't find a stand alone NP3 cam pin, but a WMD NiB cam pin costs $10.00, a stock cam pin runs around $5.00, and I found a teflon coated for $12.99. Duffy did advise that Robar charges nearly $10.00 to NP3 the cam pin, that would be on top of the cost of the pin and machining the dimple. So $17.00 isn't an outlandish price.
Is it worth it? I don't know, there are a lot of manufacturers who sell 'premium' parts for these rifles, and many folks seem to think those parts are worth it.
The reality is that if you're worried about spending $17 on this part, you're not the one this part is made for. If you can't afford paying an extra $12 for a premium part; you can't afford to shoot your rifle enough for that part to matter. Move on.
jackblack73
08-17-20, 09:48
Is his the $12-$14.00 you pay for the dimple? Get me a fact.
Why do you keep saying this? You must know it’s not true if you’ve been reading the thread. Most of that cost is not for the dimple but for the NP3 finish.
P2Vaircrewman
08-17-20, 09:52
Since there is no knowledge of how many rounds this part may extend bolt life and since any cam pin will eventually ware, but how much ware is too much and since we don't want a failure at an inopportune time it would seem the best course of action is to replace the cam pin frequently. Perhaps replacing the cam pin every 5000 rounds with a $5.00 stock pin is the better option. Or actually measure and keep track of cam pin ware and change it at some determined ware point. All of this seems to disregard the effect of ware in the cam pin bore which is also occurring.
Dr. Bullseye
08-17-20, 14:55
Why do you keep saying this? You must know it’s not true if you’ve been reading the thread. Most of that cost is not for the dimple but for the NP3 finish.
Why do you keep denying it is $19.00? What makes that cam pin better than a $4.50 cam pin marked with a pen? You and all you others simply cannot supply one fact supporting your case. "NP3 finish" what is that? Why should anyone care? Do you have just one scrap of evidence, one fact that it is better? Or are you going to talk about reputations and how long you have been in the business? Those are all diversions. You need facts and have presented none. The originators of this thread introduced an interesting idea on cam pin wear which is worth testing. They are to be commended for that but nothing else.
Dr. Bullseye
08-17-20, 14:59
I didn't bring them up as a topic of discussion, I brought it up to give them a frame of reference as to why they shouldn't be concerned with your opinion or remarks. No one cares if you mark your cam pins or not, and no one has said you had to. Go back and read Ned's post, or don't, and continue on ignoring the facts that have been laid out in front of you by them.
Just so we are on the same page, copy and past just the facts you mention in your next post, please.
Dr. Bullseye
08-17-20, 15:01
I didn't bring them up as a topic of discussion, I brought it up to give them a frame of reference as to why they shouldn't be concerned with your opinion or remarks. No one cares if you mark your cam pins or not, and no one has said you had to. Go back and read Ned's post, or don't, and continue on ignoring the facts that have been laid out in front of you by them.
Well then, as a frame of reference, what was your experience with Ultradynes since you are an expert?
Ned Christiansen
08-17-20, 16:08
I can't help but agree that some data would be nice..... right now it's just logic and theory, but pretty strong in those areas-- but that's just my opinion.
Thing is, to get actual data on this or anything takes a tremendous amount of time and money, same as with any of the many other incremental, theoretical improvements that we fuss over at times (that applies to gun people car performance people, bike / bicycle people, et al).
So my take is "can't hurt, might help". For you guys talking about marking your own, I would absolutely not do it with a punch, don't go hitting a hardened part with a hardened tool. Dremel a little arrow into it, or a dot or something, lightly.
I have done extensive testing using custom ground gage pins to track when wear becomes a concern. Some people have a philosophy where they shoot until something breaks or fails. I like to know before something breaks or fails so I can avoid a catastrophic malfunction.
It sounds like there is data, but it did not originate free of cost and there is no obligation to freely provide it. I am grateful that he gave the free tip to mark cam pins. I could not ask for more.
nightchief
08-17-20, 18:26
I can't help but agree that some data would be nice..... right now it's just logic and theory, but pretty strong in those areas-- but that's just my opinion.
Thing is, to get actual data on this or anything takes a tremendous amount of time and money, same as with any of the many other incremental, theoretical improvements that we fuss over at times (that applies to gun people car performance people, bike / bicycle people, et al).
So my take is "can't hurt, might help". For you guys talking about marking your own, I would absolutely not do it with a punch, don't go hitting a hardened part with a hardened tool. Dremel a little arrow into it, or a dot or something, lightly.
Oops. :eek: Guess I'll be replacing the cam pin sooner than later.
You can buy very hard chrome bolt cam pins. NP3 eventually wears.
I've seen literally hundreds (if not thousands) of M16s and M4s that will eventually need new bolts and cam pins. I've broken two bolts in over 40 years of shooting the M16/M4 family -- one to sheared lugs and one separating at the cam pin hole on an SF CQB School student carbine with an unknown and ungodly round count.
Machines eventually need high-wear part replacement. Nothing designed to function with high-stress and high-pressure parts lasts forever.
All, I can say is: "Congratulation" to the two guys that thought this up.
Given the tolerances between the pin and the cam slot, and how much wear you are going to see before tossing the cam pin, and the fact that the cam slot is a 45 degree helix, your saving nothing.
The cam slot is a 45 degree helix and symmetrical, other than the length of the straight sections. That means the major contact area on the cam pin is at 45 degrees on the front side (unlocking), and the minor wear area is at 45 degrees on the back side (locking).
Guess what happens if you rotate the cam pin 180 degrees? The two contact areas switch sided, but the area that contacts remains the same.
Keeping the cam pin in one orientation would theoretically half the life, but realistically, I don't think it matters one wit.
There is always a lot of controversy about the videos and content from my courses. It's not intentional, nor am I offended if people politely disagree.
Marking the cam pin has less to do with saving the life of the cam pin and more to do with extending the life of the bolt.
The more you do to minimize wear and slop between the bolt and cam pin, the longer the bolt should last.
When you allow excessive amounts of slop between the cam pin and the bolt, you increase the chance of stretching or breaking the thin webbing at the edges of the cam pin bore.
I have done extensive testing using custom ground gage pins to track when wear becomes a concern. Some people have a philosophy where they shoot until something breaks or fails. I like to know before something breaks or fails so I can avoid a catastrophic malfunction.
FWIW, I mark my cam pins with a starter drill bit.
Thank you for the explanation. I just received my PA back in stock notification for the FCD cam pins to go along with my new bolt heads.
Edit: Thanks Chad,Roger and Ned for your sharing your valuable input.
jerrysimons
08-18-20, 00:42
All, I can say is: "Congratulation" to the two guys that thought this up.
Given the tolerances between the pin and the cam slot, and how much wear you are going to see before tossing the cam pin, and the fact that the cam slot is a 45 degree helix, your saving nothing.
The cam slot is a 45 degree helix and symmetrical, other than the length of the straight sections. That means the major contact area on the cam pin is at 45 degrees on the front side (unlocking), and the minor wear area is at 45 degrees on the back side (locking).
Guess what happens if you rotate the cam pin 180 degrees? The two contact areas switch sided, but the area that contacts remains the same.
Keeping the cam pin in one orientation would theoretically half the life, but realistically, I don't think it matters one wit.
The contact points of the bolt carrier cam track on the cam pin thats wears the grooves into the cam pin flips around with the cam pin, sure (whatever its shape), but the focus of the SOTAR cam pin is eliminating the shock loading that happens with the pivoting of the cam pin inside the bolt at the extremes of movement (the staring and starting and stopping) by taking up the slop usually made by the space double sided grooves form. That pivoting movement functions to pry the bolt apart at its weak point as the assembly is jerked back and forth. Equating the way a single side of the cam pin is marked by the carrier cam pin pathway with how the forces inside the assembly interact at the extremes of its range of motion is flawed.
Half the life? Hardly! Nobody here is making that type of claim for a gain. It's in error to claim that magnitude to its detriment.
The contact points of the bolt carrier cam track on the cam pin thats wears the grooves into the cam pin flips around with the cam pin, sure (whatever its shape), but the focus of the SOTAR cam pin is eliminating the shock loading that happens with the pivoting of the cam pin inside the bolt at the extremes of movement (the staring and starting and stopping) by taking up the slop usually made by the space double sided grooves form. That pivoting movement functions to pry the bolt apart at its weak point as the assembly is jerked back and forth. Equating the way a single side of the cam pin is marked by the carrier cam pin pathway with how the forces inside the assembly interact at the extremes of its range of motion is flawed.
Half the life? Hardly! Nobody here is making that type of claim for a gain. It's in error to claim that magnitude to its detriment.
There is an error in your logic.
The cam angles for locking and unlocking are equal, the bolt carrier is a cylinder and the cam pin is a cylinder. This means the contact areas as the pin moves forward are exactly the same as the contact areas as the pin moves backwards only rotated 180 degrees. That means the wear areas are exactly the same.
The increase "slop" is caused by and increase in clearance between the parts, so if you want to reduce your shock loading, you want to reduce the amount of wear. The pin is softer than the carrier so most all the wear in on the pin.
The loading during the unlocking camming is much greater that the loading during locking camming, therefore the "front" of the pin will wear faster than the "back". If you keep one side towards the front all the time, the front wear will accumulate faster than the back. If you switch pin orientation regularly, or randomly, the wear will be distributed equally on the front and the back of the pin, so on average the amount of wear on any one face will be less.
Also, the cam pin does not bottom out in the cam track during locking, the carrier stops on contact with the barrel extension well before the pin reaches the back end of the cam slot, so this side doesn't wear at all. The highest load on the cam pin is at the end of unlocking when the pin bottoms out at the front of the cam slot. Again, randomly switching the orientation of the cam pin will reduce the wear on any one side.
If you want to reduce the loads on the hole in the bolt, the way to achieve that is find a way to reduce the amount of wear on the face of the cam pin that faces forward. Flipping it 180 degrees every now and again is a better way to do that than leaving one face always facing forward....
Personally, I think liberal use of a good lubricant in the cam slot is a most cost effective way of achieving the desired end.
jerrysimons
08-18-20, 09:50
There is an error in your logic.
The cam angles for locking and unlocking are equal, the bolt carrier is a cylinder and the cam pin is a cylinder. This means the contact areas as the pin moves forward are exactly the same as the contact areas as the pin moves backwards only rotated 180 degrees. That means the wear areas are exactly the same.
The increase "slop" is caused by and increase in clearance between the parts, so if you want to reduce your shock loading, you want to reduce the amount of wear. The pin is softer than the carrier so most all the wear in on the pin.
The loading during the unlocking camming is much greater that the loading during locking camming, therefore the "front" of the pin will wear faster than the "back". If you keep one side towards the front all the time, the front wear will accumulate faster than the back. If you switch pin orientation regularly, or randomly, the wear will be distributed equally on the front and the back of the pin, so on average the amount of wear on any one face will be less.
Also, the cam pin does not bottom out in the cam track during locking, the carrier stops on contact with the barrel extension well before the pin reaches the back end of the cam slot, so this side doesn't wear at all. The highest load on the cam pin is at the end of unlocking when the pin bottoms out at the front of the cam slot. Again, randomly switching the orientation of the cam pin will reduce the wear on any one side.
If you want to reduce the loads on the hole in the bolt, the way to achieve that is find a way to reduce the amount of wear on the face of the cam pin that faces forward. Flipping it 180 degrees every now and again is a better way to do that than leaving one face always facing forward....
Personally, I think liberal use of a good lubricant in the cam slot is a most cost effective way of achieving the desired end.
Agreed a good lube that stays put like a light grease is ideal there. But the error here is thinking this is about cam pin life and not bolt life. The carrier track is not the only wear point on the cam pin, the twisting open action wears the cam pin inside the bolt hole. That is where the slop can be real bad especially if you started with a wiggly cam pin inside the bolt hole to begin with. The bolt is holding onto the pressurized case and carrier is flying rearward, the connection point between the two is a shaft inside a hole 90* to the momentum force, when cam pin hits bottom in the carrier track during unlock, the cam pin applies pry forces to the bolt at the bottom-muzzle-side and the top-buttstock-side of the bolt cam pin hole via force applied on the top-muzzle-side of the cam pin by the carrier track (this same principle is why Knights reinforced the E3 bolt at the cam pin hole by reducing the diameter of the cam and cam pin hole hole). The wear on the reverse side of the cam pin at the carrier cam pin track is not really at issue, like you said because the cam pin only bottoms out in the track on unlock. The slop issue is the wear of the cam pin inside the bolt hole and the pry forces that happen during the shock loading of unlocking.
Dr. Bullseye
08-18-20, 12:52
I can't help but agree that some data would be nice..... right now it's just logic and theory, but pretty strong in those areas-- but that's just my opinion.
Thing is, to get actual data on this or anything takes a tremendous amount of time and money, same as with any of the many other incremental, theoretical improvements that we fuss over at times (that applies to gun people car performance people, bike / bicycle people, et al).
So my take is "can't hurt, might help". For you guys talking about marking your own, I would absolutely not do it with a punch, don't go hitting a hardened part with a hardened tool. Dremel a little arrow into it, or a dot or something, lightly.
In establishing mil spec the government who originally ordered the M16 established a standard for some reason. They must have done testing. Just assuming a product is better than mil spec because it is harder or has a harder coating may be wrong. An AR is a machine. All parts have to work together. If you make one part harder in an effort to make it better it may wear down connecting parts quicker. Metallurgists know this so do engineers who design rifles. But aftermarket guy sometimes do not get this. This miss-match happens in the automotive world where, for instance, someone builds an oil pump with a harder slot to fit into a cam dish. Then the cam dish wears away causing failure but the pump is still intact. Mil spec is mil spec for a reason. If this were to happen in this case the hole in the bolt may actually wear faster with a hardened cam pin. For my money, if you advance a component as better than mil spec you really need proof for this, not logic, not opinion.
Agreed a good lube that stays put like a light grease is ideal there. But the error here is thinking this is about cam pin life and not bolt life. The carrier track is not the only wear point on the cam pin, the twisting open action wears the cam pin inside the bolt hole. That is where the slop can be real bad especially if you started with a wiggly cam pin inside the bolt hole to begin with. The bolt is holding onto the pressurized case and carrier is flying rearward, the connection point between the two is a shaft inside a hole 90* to the momentum force, when cam pin hits bottom in the carrier track during unlock, the cam pin applies pry forces to the bolt at the bottom-muzzle-side and the top-buttstock-side of the bolt cam pin hole via force applied on the top-muzzle-side of the cam pin by the carrier track (this same principle is why Knights reinforced the E3 bolt at the cam pin hole by reducing the diameter of the cam and cam pin hole hole). The wear on the reverse side of the cam pin at the carrier cam pin track is not really at issue, like you said because the cam pin only bottoms out in the track on unlock. The slop issue is the wear of the cam pin inside the bolt hole and the pry forces that happen during the shock loading of unlocking.
The ultimate cause of a "wiggly" cam pin will be cam pin wear. So, if you want to reduce the wiggle, you have to keep the surfaces as close to original shape as possible, which means you have to reduce the wear on the cam pin, i.e., prolong the life of the cam pin.
That wear is going to be the three places in red in the below drawing as the carrier tries to twist the cam pin out of the bolt. After a time the areas in red will become below the original surface and the amount of play will increase
Rotating the cam pin 180 degrees on a regular bases distributes the wear over multiple areas and prolongs the time before the slop becomes a problem.
63440
Knight's idea of reducing the diameter of the cam pin and its hole in the bolt is just a simple way of increasing the amount of material in the bolt to resist the twisting force. And, you pay for that with increased stress on the cam pin. But, cam pins are cheaper than bolts, so there is net gain there.
So my take is "can't hurt, might help".
From my thumbnail analysis, I come to the exact opposite opinion, "can't help, might hurt" . . .
Ned Christiansen
08-21-20, 09:57
Well..... good logic going both ways here...... I can't say that I am totally convinced one way or the other. I'm going to do it, mark a couple cam pins, but it won't be a legit test because there are so many other factors (among them starting with used parts), and really, I'm not gonna get round counts on multiple guns that would constitute real testing. The only solution here is half of us do it and half don't, everyone do your shooting in white lab coats, keep rounds counts and other conditions noted, and report back in five years.... :-)
I note that LanTac is also doing something similar--- FWIW. When I think about how the rearward-moving carrier impacts the cam pin I still think better-mated surfaces at that impact point (front of cam track) could be an advantage...... mated surfaces between the cam pin and cam track as the bolt is rotated also seem advantageous.... I have not as yet looked one over having this conversation in mind, I sorta need to work that in I guess.
If the cam helices were different between the opening and closing ramps, or the carrier was square, then, yes there would be a benefit to keeping the cam pin in one orientation.
However, the cam helices are at the same angle and the carrier is round. That means the surface presented to the cam pin is identical, coming or going.
In either case, I highly doubt it make any difference one way of another.
If the cam helices were different between the opening and closing ramps
Is this the case with the LMT Enhanced carrier?
Is this the case with the LMT Enhanced carrier?
No, They changed the helix angle and altered the length of the straight portions, but the opening and closing helices are the same angle.
This is an example of a non-symetrical cam path:
63575
The locking cam is steeper than the unlocking cam. And, yes the lead-in helix is the same, but at 67degrees, 6 minutes rotation the two cam curves diverge.
No, They changed the helix angle and altered the length of the straight portions, but the opening and closing helices are the same angle.
This is an example of a non-symetrical cam path:
63575
The locking cam is steeper than the unlocking cam. And, yes the lead-in helix is the same, but at 67degrees, 6 minutes rotation the two cam curves diverge.
Much appreciate the education sir... :)
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